Equations arising from substitution in formulae...help?

Question

I have to find the value or r. correct to one decimal place, if:
C= 2лr and C = 120

but i dunno how to get the answer though i looked in back and the answer is 19.1
л is supposed to symbolize pi

Answer 1

C=2(pi)r
C=120
just substitute the 2nd equation to the 1st
therefore
120=2(pi)r
then by dividing both side by 2(pi) we can have the value of r
(120)/(2(pi))=r
19.1=r
which is your answer

Answer 2

Since C = 2*pi*r and C = 120, therefore:

2*pi*r = 120. Hence r = 120/(2*pi) = 60/pi = 19.09090... = 19.1 (using pi = 22/7 approx)